Separation is an industrial process which is often employed in the food industry. Fat separation is, for example, employed for milk and whey. The separation usually takes place in a centrifugal separator.
In its interior, the separator has a number of conical disks disposed in a stack with a well-defined distance between the disks. The disks are provided with distribution holes which are vertically arranged. Through these holes, the milk or whey enters from the inlet in the actual separation section and is subjected to centrifugal force. Particles and impurities in the milk or whey move outwards along the surfaces of the disks and are accumulated in a sedimentation space. The lighter phase of the liquid food, i.e. the fat/cream moves inwards along the surfaces of the disks towards the axis of rotation and is conveyed out from the separator through an axial outlet. The heavier phase, which may consist of skim milk or whey which has been freed of fat globules moves outwards along the surfaces of the disks and is accumulated at an outlet. Modern separators may have different constructive concepts. The present invention may be employed for all types of centrifugal separators.
A common use for the separation process is separating milk, where the milk is separated into a skim milk phase and a cream phase. The milk may thereafter be standardised, for example into consumer milk at the desired fat content in that a part of the cream phase is recycled to the skim milk phase.
The separation process is also employed to extract fat from whey. Whey is a by-product in cheesemaking and, since roughly a third of the world's milk production is employed for cheesemaking, this implies that almost a third of all milk becomes whey. Whey which has previously only been used as animal feed and as fertiliser risked becoming an environmental problem. Today, whey has increasingly come to be considered as a valuable raw material for producing protein with a high nutrient content. The fat which is extracted from the whey is normally recycled back to cheesemaking or to other parts of the dairy process.
It is of interest to increase the fat separation in all separation processes, above all in whey separation. By separating more fat out of the whey, it is possible in a subsequent production of protein, to achieve a more efficient and more economical process.
Previous attempts to increase the yield in the light phase, i.e. to extract more fat from milk or whey, have entailed the employment of larger separators. Larger separators involve large capital costs, both as investment costs and as running costs.